Process of recovering rubber from rubber-waste.



UNITED STATES j PATENT OFFICE. I

WILLIAM A. KONEMAN, OF CHICAGO, ILLINOIS.

PROCESS OF RECOVERING RUBBER FROM RUBBER- WASTE.

Specification of Letters Patent.

Patented Oct. 30, 1906.

Application filed March 28, 1906. Serial No. 308,418-

To a whom aft-may concern:

Be it known that I, WILLIAM A. KoNE- MAN, a citizen of the UnitedStates, residing application for Letters Patent, Serial No.

282,019, filed October 9, 1905, I have discovered a treatment of therubber which greatly im roves its quality, as hereinafter described.

aforesaid process involves, broadly stated, boiling the finely-dividedmaterial in a mineral-acid solution with the addition of a halogen saltof the alkaline group, suchas so or calcium chlorid without setting freein a gaseous state the "chlorin, bromin, or iodin, chlorid of sodiumbeing the salt preferably employed.- After removing the acid anddissolved matter from the rubber it is boiled in a solution of alkalinesalt and washed and dried.

. While the present improvement has been developed, as statedfinconnection with the aforesaid salted-acid process, it is not myintention to limit its use to that particular con nection, inasmuch asit is found to produce the same advantages, even though in a minordegree, when used with any process involving the subjection of thematerial to the ac tion of an acid or an alkaline solution.

- The recovery of rubber as practiced by the more or less successfulprocesses generally knownin the art maybe stated to consist in thetreatment of the finely-divided rubber- 4o scrap either in an acid or analkaline solution ,l or in both of such solutions in succession, lat"various tem eratures and under various pressures. he rubber thusrecovered is in a more or less resinified condition and is lacking inthe desirable qualities of virgin rubber which determine the value ofthe latter-namely, those of tensile strength and elasticity and thecharacteristic commonly It isthis fiber condition in rubber, whichmustshow itself in tearing, that largely determines the amount ofwear andtear which articles made from" it. will stand. By ny aforesaid previousprocess I have aimed more particularly at obtaining in a high degree thequalities in the recovered that such deleterious action is prevented,without interference with the solvent action product of elasticity orresiliency and tensile strength. By my present improvement the tensilestrength of the product is mate: rially increased and there is impartedto it a fiber quality, of the character ofinterlaced atoms, whichrenders the rubber resistant to tearing action, and consequentlyincreases the durability and utility of articles manufactured from it.

The derogatory effect of the acid reaction in the usual acid treatmentemployed for recovering rubber from rubber-waste and that of thealkaline reaction in the usual alkaline tratment for the same pur oseare found to be due to depriving the rub erof those resinous andoleaglnous constituents which in the virgin gum cause proper cohesion ofthe caoutchouc atoms. The object of my present improvement is to preventsuch deleterious chemical reaction without impairing the solvent actionof the solution employed on the uncombined sulfur, vegetable fiber,certain mineral compounds, &c., contained in the material treated, and Ihave discovered of the solution employed, by bringing into contact withthe finely-divided rubber a reducing agent in the form of a miXableIlYdIO'. carbon, preferably in the form of either coaltar or vegetabletar, in such. proportion as will produce the desired result. 1

(My invention therefore consists, broadly, in adding to therubber-waste, either while it is in the acid orthe alkali solution orbefore introducing it into the solution", a suitable proportioubf a'suitably-adherent hydrocarbonv I find that according as the rubber 'ofthe waste material under treatment is more or less pure the quantity ofthe tar required is greater or less. Thus when the material treated inthe solution is scrap from automobile, bicycle, or solid vehicle tiresit is desirable to use the tar in the proportion of from three to fiveper cent. of the material, while with inferior scrap, as that fromrubber hose and belting, about two per cent. of the ta'ris 1 sufficient,and for boot and shoe scrap about one and one-half to two and'one-halfper cent. of the tar is a suitable proportion, Where the acid process isemployed, the tar; 1;, may be added to the acid solution, though thenthe latter should be subjected to, agitea tion while boiling and actingon the rubber- I1 waste material undergoing treatment; but unlessagitation is practiced the tar should be thoroughly mixed with the scrappreparatory to subjecting the latter to the treatment in the solution.Where the alkaline process is employed, an adherent hydrocarbon, such astar or a vegetable balsam, is to be mixed with the scrap beforesubjecting the latter to the action of the solution, and no hydrocarbonmay be used in this case which will saponify under the action of thealkali.

. ble to assure intimate contact.

The product resulting from the acid or the alkaline treatment will showthe desired fiber character if the proper proportion of tar is used.Although the fiber-producing result of my improvement is obtainable withthe usual processes involving treatment of the material in the acid andalkaline solutions referred to, by such treatment the fiber will be weakin proportion to the degree of resinification of the caoutchoucresulting therefrom, whereas when employed in connection with myaforesaid salted-acid treatment of the rubber, whereby resinification ofthe caoutchouc is avoided, the beneficial result of the use of thereducing agent is obtained in the maximum degree.

It is essential that the hydrocarbon employed shall be of a nature toattach itself to the rubber particles and permeate the rubber during theboiling period. I find the best materials for the purpose to be, in theorder named, as follows coal-tar, coal-tar pitch thinned inoil,vegetable tar, melted or thinned vegetable pitch, vegetable balsams,dissolved rosin, and invert-sugar. Whichever agent is employed isdependent upon the character of stock, fiber, and softness of resultantstock desired. As the greater percentage of the hydrocarbon employedfinally remains with the solution, it is desirable to save the solutionfor successive use, in which case a lesser amount of the hydrocarbon maybe added to the next charge... Tar will rise to the surface of an acidsolution, while it sinks in an alkaline solution, which makes itdesirable in either treatment to work the stock in as thick or slushycondition as possi- Too thin a condition of solution will prevent properresults with any one of the hydrocarbons mentioned, as in that casetheir action is not sufficiently powerful, owing to lack of contact andtoo great dilution, to assure full benefits unless used in such quantityas to seriously interfere with the regular solvent and devulcanizingaction of the solution employed. After the proper action on the rubberhas taken place the stock may be thinned down and washed to any extentdesired, either with hot or cold water, and shou d be washed andcleansed thoroughly bef drying, when the result is that the mate will befree from the odor of the hydrocar employed and will show a degree ofstre and amount of fiber structure which is now found only in high-gradevirgin-rubber compounds.

Even ground rubber, practically frce from. cotton or wool fiber, may betreated with the hydrocarbon in boiling water or in a weak acid oralkaline solution, and upon such treated. stock being mixed with otherstock it will impart a considerable amount of fiber to the mixed mass.Likewise low-grade virgin rubber may be greatly improved by suchtreatment, and I do not, therefore, limit my invention to the use of thehydrocarbon treatment for the purpose of treating devulcanizedrubber-scrap only.

My invention is distinguished from processes known to me of recoveringrubber from rubber waste by boiling the finely-divided waste material inan acid or an alkaline solution and treating the recovered rubber withvolatile hydrocarbons, commonly known as rubber solvents, such as thelight mineral and vegetable oils and extracts, the same includingbenzin, naphtha, turpentine, bicar buret of sulfur, chloroform, and thelike. None of these are eitheeniixable with or soluble in an aqueousacid or alkaline solution, and when used, if not under confinement, theyare expelled by boiling the solution. Moreover, they have nofiber-producing effeet on the rubber, which is an all-im ortant resultof my invention. I therefore ciisclaim such use of these volatilehydrocarbons. The hydrocarbon required for my purpose must possess as anessential quality that of being mixable with or solvent in, or bothmixable with and solvent in, the aqueous acid or alkaline solution inwhich the material is boiled, tar, for example, being in part mixableand in part soluble in the acid solution, while resin is entirelysoluble in an alkaline solution.

What I claim as new, and desire to secure by Letters Patent, is

1. The process of treatin finely-divided rubber, which consists inboiling the same in a suitable liquid and adding thereto a mixable fixedhydrocarbon such as tar, itch, resin or balsam, for the purpose setforth 2. As a step in the recovery of rubber from rubber-waste materialby treating the material in a suitable aqueous chemical solution, addingto said material a suitable proportion of hydrocarbon of the characterdescribed, for the purpose set forth.

3. As a step in the recovery of rubber from rubber-waste material bytreating the material in a suitable aqueous chemical solution, adding tosaid material a suitable proportion of tlalr, pitch or balsam, for thepurpose set fort rubber-waste material, which consists in boiling thefinely-divided material with the addi "ion thereto of a suitableproportion of hydro- 4. The process of recovering rubber from carbon ofthe character described in a suitable aqueous chemical solution, andremovg the dissolved and decomposed fiber, for the purpose set forth.

5.--The ing the finely-divided material with the addition thereto of asuitableproportion of mixable hydrocarbon in a mineral-acid solutioncontaining a halogen salt of the alkaline group, such as sodium orcalcium chlorid, and removing the dissolved and decomposedfiber, for thepurpose set forth.

6. The process of recovering rubber from rubber-waste material, whichconsists in boiling the finely-divided material with the additionthereto of a suitable proportion ofvmixable hydrocarbon in amineral-acid solution containing a halogen salt of the alkaline processof recovering rubber from rubber-waste material, which consists -111bo1lthe acid and dissolved matgroup removi'n fiber, then boiling therubber.

ter from the ru in a solution of alkaline salt, and washing and dryingthe product, for the purpose set forth.

7. The process of treating finely-divided rubber which consists inboiling the same in an acid solution and adding thereto a mixable fixedhydrocarbon, such as tar, itch, resin or balsam, for the purpose setforth.

8. The process rubber which consists in boiling the same in asalted-acid solution and adding thereto a mixable fixed hydrocarbon,such as tar, pitch, resin or balsam, for the purpose set forth.

WILLIAM A. KONEMAN. In presence of- J. H. LANDES,

L. HEISLAR.

of treating finely-divided

